Communications between two cellular radiotelephone (also referred to herein as a mobile terminal and a mobile station) users is established using cellular systems. By example, in the Time Division, Multiple Access (TDMA) system known as IS-136 (IS-136.1, Rev. 0, May 17,1995) various network systems are classified into three groups: public, private, and residential networks. Private and residential networks may also be referred to as non-public networks. Typically, there are two public cellular systems in one geographical area. In addition, there may be one or more non-public cellular systems available to users within the same geographical area. Also, service providers operating in other bands, such as the 1900 MHz band, may also be available.
The two public cellular systems within one geographical area are conventionally referred to as the A-system and the B-system. For example, in both the New York and Los Angeles metropolitan areas there are two public cellular systems. Each of these systems has its own unique identity, referred to as the SID (System Identification).
Generally, the cellular radiotelephone can operate at any given time in one of the two available public systems, and a display of the radiotelephone will typically have indicators (i.e., A and B icons) for indicating to the user which system is currently being used.
One of the public systems is always referred to as the "home system" of the radiotelephone, or more specifically as the home system of the radiotelephone's Number Assignment Module (NAM). Whether the home system is A-type or B-type depends on the parameters of the currently selected NAM.
One purpose of non-public systems is to provide specialized telecommunications services to radiotelephone users. The primary non-public system types include Wireless Business Systems, Limited Service Areas, and Residential Cellular Telephones.
In the Wireless Business System (WBS) application, connections for a closed group of users are typically switched through an existing PBX or through the public switched telephone network (PSTN). This type of system provides capabilities for offering specific features that can be highly integrated with other telecommunications services used by the group, with the goal of providing all of the capabilities of a desk telephone. Examples of these services include: voice mail integrated into an existing wired PBX; centralized speed dial lists; and simplified private network access.
In the Limited Service Area (LSA) application, a closed group of users may receive special billing considerations and custom features and services while within the coverage range of the private or semi-private system. Public subscribers not belonging to the closed group would receive service at standard billing rates. An LSA may be deployed at shopping malls, airports, sports facilities, hotels, etc. Full-time staff at such a facility may subscribe to the LSA service, while customers and itinerant visitors receive standard public wireless service over the same network.
The Residential Cellular Telephone (RCT) application is intended for use within a residence, and functions as an enhanced wireless telephone set. The RCT application is intended to provide users with a single handset which can be used as a cordless telephone when operated in conjunction with a home or neighborhood base station within a residential or office environment. The RCT application is also intended to provide a standard cellular mobile station when operating within the cellular environment, or as part of a Wireless Business System (WBS). When the handset is used as a conventional cordless telephone, the associated home or neighborhood base station communicates with the cellular network to assure that a user's calls are automatically forwarded to the user's landline telephone number.
In a document entitled "TDMA Forum, Implementation Guide: Non-Public Mode Operation and Selection in IS-136 Compliant Mobile Stations", Version 2.0, Mar. 9, 1995, a number of system operators have described non-public mode and selection requirements for mobile stations compliant with TIA Interim Standards IS-136 and IS-137. The document is said not to mandate any specific implementation, but instead to promote a similar level of services for all mobile station users.
FIG. 1 is based on FIG. 1.3-1 of the above-referenced TDMA Forum document, and illustrates a mobile station reference model for non-public mode operation. More particularly, FIG. 1 illustrates the various elements required to support the loading and management of PSIDs/RSIDs in an IS-136 compatible mobile station. To facilitate the discussion, the following conventions are used.
PSID is the numeric value of a Private System ID. A PSID is always be associated with the appropriate System Identification Code (SID), System Operator Code (SOC), Mobile Country Code (MCC), or International status (Null), according to Section 8.3.4 of IS-136, during the process of storage or verification.
RSID is the numeric value of a Residential System ID. An RSID should always be associated with the appropriate SOC, MCC, or International status (Null), according to Section 8.3.5 of IS-136, during the process of storage or verification.
Alpha Tag is an alphanumeric designator associated with a PSID/RSID. This designator may be used when a user is alerted or is presented a choice regarding a specific PSID/RSID. The numeric PSID/RSID values are said to be used solely for the Selection/Reselection processes, and should not be presented to the user. The alphanumeric designator (i.e., the Alpha Tag) is derived from either a Test Registration Alphanumeric PSID/RSID, from an alphanumeric tag entered with the PSID/RSID during NAM programming, or from a default Alpha Tag used if neither of the previous two sources are available.
In a similar manner, the term Alpha Tag is used to refer to the alphanumeric designator associated with a given SID, whether the designation is derived from the Alphanumeric SID available from the system or is derived from an Alpha Tag entered during NAM programming. The numeric SID is not presented to the user, but rather, the Alpha Tag associated with the SID.
The MS Reference Model for Non-Public Mode Operation of FIG. 1 is divided into three major functions: (1) PSID/RSID acquisition, (2) user review and selection of PSIDs/RSIDs, and (3) the selection and reselection processes. These three elements are said to be administered by a common PSID/RSID Management Function. As presented, FIG. 1 is intended to aid in describing the storage, display, prioritization, and selection of PSIDs/RSIDs.
The management of the storing, displaying, selecting, and prioritizing PSIDs/RSIDs is facilitated by constructing a list within a PSID/RSID logical management block. Each list is NAM specific and is dynamic with respect to the fact that it is reconstructed or updated each time the contents of a corresponding NAM, Test Registration, or Registration Accept PSID/RSID list changes. The "common" PSID/RSID list is called upon to support the selection/reselection processes; for two user menu functions, System Select and Network Priority; and for a System ID display function. As previously described, the numeric PSIDs/RSIDs residing in this list are used for the selection/reselection process, while the Alpha Tags linked to these PSIDs/RSIDs are used for all user interactions.
The storage and purpose of each PSID/RSID acquisition method is unique. NAM programmed PSIDs/RSIDs are intended to be entered by a service technician and will be, in general, permanent, although their Alpha Tags may be updated. The Test Registration method is invoked by the user and is primarily used for acquiring new PSIDs/RSIDs. Each PSID/RSID acquired by a Test Registration is stored individually and replaces a previously stored PSID/RSID within the Test Registration storage area if the storage area is full. Finally, the Registration Accept method is system initiated and can automatically load a PSID/RSID set without any user interaction. For this method, a new list overwrites any previously stored PSIDs/RSIDs within the Registration Accept storage area. As FIG. 1 depicts, each NAM supporting non-public mode operation will have one of each of these three storage areas.
As can be appreciated, as the complexity of cellular telephone networks increases, and as user's are given more options for communicating through various systems, including public and non-public systems, it has become important to provide a simple and efficient user interface enabling a user to manage, prioritize, and select between available systems.